Today's consumer electronics market frequently demands complex functions requiring very intricate circuitry. Scaling to smaller and smaller fundamental building blocks, e.g. transistors, has enabled the incorporation of even more intricate circuitry on a single die with each progressive generation. Semiconductor packages are used for protecting an integrated circuit (IC) chip or die, and also to provide the die with an electrical interface to external circuitry. With the increasing demand for smaller electronic devices, semiconductor packages are designed to be even more compact and must support larger circuit density. For example, some semiconductor packages now use a coreless substrate, which does not include the thick resin core layer commonly found in conventional substrates. Furthermore, the demand for higher performance devices results in a need for an improved semiconductor package that enables a thin packaging profile and low overall warpage compatible with subsequent assembly processing.
Furthermore, for the past several years, microelectromechanical systems (MEMS) structures have been playing an increasingly important role in consumer products. For example, MEMS devices, such as sensors and actuators, can be found in products ranging from inertial sensors for air-bag triggers in vehicles to micro-mirrors for displays in the visual arts industry and, more recently, in mobile applications such as accelerometers for determining the orientation of the mobile device or air pressure sensors for altitude sensing. As these technologies mature, the demands on precision and functionality of the MEMS structures have escalated. For example, optimal performance may depend on the ability to fine-tune the characteristics of various components of these MEMS structures. Furthermore, consistency requirements for the performance of MEMS devices (both intra-device and device-to-device) often dictate that the processes used to fabricate such MEMS devices need to be extremely sophisticated.
Although packaging scaling is typically viewed as a reduction in size, the addition of functionality in a given space is also considered. However, structural issues may arise when attempting to package semiconductor die with additional functionality also housed in the package. For example, the addition of packaged MEMS devices may add functionality, but ever decreasing space availability in a semiconductor package may provide obstacles to adding such functionality.